Film cut-out



March 8, 1927.

H. E. BUTLER FILM CU- OUTI Filed n n-:weh 51, 192s Inventor: Hemjg E. Butler, M# His Attorney.

Patented Mar. 8, 1927.

UNITED STATES PATENT OFFICE.

HENRY E. BUTLER, OF SCOTIA, NE'W YORK, ASSIGNOE TO GENERAL ELECTRIC COM- PANY, A CORPORATION OF NEW YORK.

FILM CUT-OUT.

Application filed March 31, 1926.

The present invention relates to film cutouts for electric circuits such as are used in series incandescent street lighting whereby in case the circuit becomes interrupted 5 at any one of the lamps in series, the film cutout serves automatically to provide a new or shuntcircuit about the point of interruption. This serves to permit current to pass through the other or unruptured lamps in l the series so that the breaking down of one or more of a number of lamps in series does not interfere with t-he proper functioning of the remaining lamps.

Film cutouts comprise two conductor l terminals arranged in juxtaposition but insulated from each other by a member of a character such that when the flow of current through the lamp is interrupted the increased potential resulting from such interruption operates to break down or puncture the member and allow current to flow around the lamp.

The invention relates particularly to film cutouts of the type disclosed and claimed in my Patent No. 1,548,656, dated August 4, 1925, film cutouts of this type being known now as magazine film cutouts.

The object of my invention is to provide an improved magazine film cutout, and for a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing, Fig. 1 is a sectional view of a series street lighting socket provided with a magazine film cutout embodying my invention; Fig. 2 is a detail perspective view of a film structure and its protecting casing, and Fig. 3 is a detail sectional view on a l0 greatly enlarged scale of the film material.

Referring to the drawing, 10 indicates a receptacle having a base 11 and a bracket 12 provided with a threaded end 13 adapted to be connected to a lamp post bracket.

Carried by base 11 are two opposed spring contacts 14 and 15 to which are connected binding posts 16 and 17 which receive the series line terminals, 18 indicates a lamp socket having a threaded shell 19 adapted to 5U receive the threaded end 2O of an incandescent lamp 21. Shell 19 forms one terminal connection for the lamp, the other terminal being formed by a central contact 22. Contact 22 and shell 19 are connected by screws 23 and 24 to spring contacts 25 and 426 which Serial No. 98.888.

are adapted to be inserted between spring contacts 14 and 15 to form the circuit connections for connecting the lamp into the series circuit and also to form a supporting means for the lamp socket, Spring contacts 25 and 26 have parallel outer ends as indicated at 27 and 28 below which are bowedout portions 29 and 30. Below bowed portions 29 and 30 the contacts have long, straight substantially-parallel portions 31 and 32. 33 is an insulating plate which surrounds contacts 25 and 26 at their lower ends. Located in bowed-out portions 29 and 8O is a receptacle or capsule 84C in which is contained a roll of insulating material 35.'

The end of the insulating material extends out through a slot 86 in capsule 84: and projects up between contact ends 27 and 28 thereby serving to insulate them from each other.

As is well understood, as long as the filament of lamp 21 is in service the current flows through it, lighting the lamp in the usual manner, contacts 27 and 28, which are connected in parallel with the lamp filament, being insulated from each other by the film material 35. In case the lamp burns out or is removed the series circuit is interrupted. This builds up a potential across contact ends 27 and 28 sufficiently high to rupture the film and effect a connection between such ends. A circuit is thereby closed around the burned-out lamp and the operation of the remaining lamps in the series circuit is not interfered with.

In the use of a magazine film cutout of the type here illustrated, when the film is punctured due to a lamp having burned out, it is only necessary upon renewing the lamp, to pull the ruptured portion of the lm out from between the contact ends 27 and 28 and tear it off. This automatically brings a fresh film between the contact ends. The arrangement so far described is more fully illustrated and described in my aforementioned patent.

In the use of a magazine film cutout it happens sometimes that burrs or slight projections are formed on the opposed surfaces of Contact ends 27 and 28 so that unless care is exercised to spread the contacts apart when renewing the film it may happen that the burrs will rupture the film sufficiently to interfere with the operation of the lamp. More specifically the object of my invention is to overcome this difficulty and to provide a means whereby even when the film is renewed b-y a careless attendant, no danger of accidental rnpturing of the film is present.

According to my invention, I provide a film material comprising an insulating material 38 upon the surface of which is located an abrasive material 39. The insulating material may be formed from thin tracing cloth or other suitable material and as an abrasive material, I have found powdered crocus to be satisfactory. The powvdered crocus may be fastened on the film material by a suitable adhesive, preferably one which is waterproof. The insulating material with the abrasive spread on its surfaces is rolled Ainto a cylinder which is located in the capsule 34- and the completed structure is used after the manner already described. In pulling the film material out between the contact ends 27 and `28 the abrasive material on the surfaces of the insulating material serves to smooth off the Contact ends and remove any burrs or projections thereon. As a result, there is no danger of the film material being injured, even though the contact ends are not spread apart somewhat when the film is being renewed; in fact, with the use of my improved film material, it is unnecessary to spread apart the contact ends when renewing the film. By pulling the film material between the contacts, the adjacent surfaces of the contacts are polished, and all burrs removed from them.

What I claim as new and desire to secure by Letters Patent of the United States,

l. An insulating member for use in film cutouts, said member comprising a strip of insulating material having an abrasive substance on its surfaces.

2. In a film cutout, the combination with a pair of contacts of a film material for use between them comprising a strip'of insulating material having an abrasive substance on its surfaces.

3. An insulating member vfor use in lm cutouts comprising a strip of cloth having an abrasive attached to its surfaces by an adhesive.

4. An insulating material for use in lm cutouts, the surfaces of said material being of an abrasive character.

In witness whereof, I have hereuntoy set my hand this th day of March, 1926.

HENRY E. BUTLER.` 

